Conventional fuel monitoring systems commonly employ a fuel sender unit, which is usually coupled to (and should not be confused with) the vehicle's fuel pump module. The fuel sender unit includes a housing containing a variable resistance fuel level sensor (e.g., a potentiometer or rheostat). The fuel level sensor has a plurality of contact pads disposed thereon, each having a different resistance. A float arm is movably (e.g., rotatably) coupled to the housing and has a float attached to an end thereof. The float buoyantly resides on the upper surface of the fuel held within the vehicle's fuel storage tank, and the arm moves (e.g., rotates) in relation to the volume of fuel within the storage tank. The fuel level sensor's resistance is dependent upon the float arm's rotational position (or height) and, thus, the volume of fuel within the fuel tank. The fuel level sensor provides a variable resistance to a conversion circuit, which generates a voltage signal related to the fuel level sensor's resistance. An output driver circuit receives the voltage signal generated by the conversion circuit and adjusts a fuel gauge (or other such display) to reflect the volume of fuel remaining in the fuel storage tank.
Although conventional fuel monitoring systems of the type described above generally produce accurate readings, this may not always be the case. Over time, contact degradation may increase the resistance of the fuel level sensor's contact pads. Thus, in systems wherein higher resistances are associated with larger fuel volumes, the fuel monitoring system may indicate that there is more fuel in the storage tank than is actually present (known as “false gas”). In addition, the conversion circuit is generally inherently more accurate at high resistance readings and less accurate at low resistance readings. Consequently, in systems wherein higher resistances are indicative of lower fuel volumes, the sender unit provides less accurate fuel level readings at lower fuel volumes (i.e., near empty). Conversely, in systems wherein lower resistances are indicative of lower fuel volumes, the sender unit provides more accurate fuel level readings at lower fuel volumes (i.e., near empty).
There thus exists an ongoing opportunity to provide a fuel monitoring system that overcomes the disadvantages noted above. In particular, it would be desirable to provide a fuel sender unit that produces relatively accurate fuel level readings at lower fuel volumes (i.e., near empty) and, in a preferred embodiment, at high fuel volumes (i.e., near full). It would also be desirable for such a sender unit to eliminate false gas indications due to contact pad degradation. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.